Explicitly add `Snap.Snaplet.Config` as an imported module for the `hint` interpreter

This addresses snapframework/snap-core#170.

Adding `Snap.Snaplet.Config` to the `setImports` module list seems to avoid the error I reported in the ticket mentioned above.

There may be a better way to fix this problem; this is just the way I managed to do it. Comments or alternative suggestions are welcome!